Pyridylazonaphthols (PANs) and pyridylazophenols (PAPs) as analytical reagents. Part II. Spectrophotometric and solvent-extraction studies of complex formations

Abstract

The reactions between 2-(2-pyridylazo)-1-naphthol (o-α-PAN), 1-(2-pyridylazo)-2-naphthol (o-β-PAN) and 2-(2-pyridylazo)phenol (o-PAP) with manganese(II), zinc(II) and lanthanum(III) and 4-(2-pyridylazo)phenol (p-PAP) with cobalt(II), nickel(II) and copper(II) have been studied. The spectrophotometric procedure based on linear extrapolation, as used by Sommer, has been critically evaluated. The results from the spectrophotometric method have been used to predict the optimum conditions for solvent extraction. It is shown that this procedure is a valuable approach for systems in which hydroxy-complexes are common.